Comment 3 for bug 1788665

Thanks for the reply. I understand that the CPU features are exposed. However, is the host-side Intel microcode exposed to the guest?

Here is my qemu command:

qemu-system-x86_64 \
  -runas user \
  -monitor stdio \
  -serial none \
  -parallel none \
  -nodefaults \
  -nodefconfig \
  -name $vmname,process=$vmname \
  -machine q35,accel=kvm,kernel_irqchip=on \
-cpu host,kvm=off,hv_vendor_id=1234567890ab,hv_vapic,hv_time,hv_relaxed,hv_spinlocks=0x1fff \
  -smp 12,sockets=1,cores=6,threads=2 \
  -m 16G \
  -mem-path /dev/hugepages \
  -mem-prealloc \
  -balloon none \
  -rtc base=localtime,clock=host \
  -vga none \
  -nographic \
  -soundhw hda \
  -device vfio-pci,host=02:00.0,multifunction=on \
  -device vfio-pci,host=02:00.1 \
  -device vfio-pci,host=00:1a.0 \
  -device vfio-pci,host=08:00.0 \
  -drive if=pflash,format=raw,readonly,file=/usr/share/OVMF/OVMF_CODE.fd \
  -drive if=pflash,format=raw,file=/tmp/my_vars.fd \
  -boot order=c \
  -drive id=disk0,if=virtio,cache=none,format=raw,aio=native,discard=unmap,detect-zeroes=unmap,file=/dev/mapper/lm13-win10 \
  -drive id=disk1,if=virtio,cache=none,format=raw,aio=native,file=/dev/mapper/photos-photo_stripe \
  -drive id=disk2,if=virtio,cache=none,format=raw,aio=native,file=/dev/mapper/media-photo_raw \
  -netdev type=tap,id=net0,ifname=vmtap0,vhost=on \
  -device virtio-net-pci,netdev=net0,mac=00:16:3e:00:01:01

By the way, the same 2D performance drop happens when I run the VM as root.